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Background: Insulin resistance carries increased risk of heart failure, although the pathophysiological mechanisms remain unclear. LV global longitudinal strain (LVGLS) assessed by speckle-tracking echocardiography has emerged as an important tool to detect early LV systolic abnormalities. This study aimed to investigate the association between insulin resistance and subclinical left ventricular (LV) dysfunction in a sample of the general population without overt cardiac disease., Methods: We investigated 539 participants who voluntarily underwent extensive cardiovascular health check including laboratory test and speckle-tracking echocardiography. Glycemic profiles were categorized into 3 groups according to homeostatic model assessment of insulin resistance (HOMA-IR): absence of insulin resistance (HOMA-IR < 1.5), presence of insulin resistance (HOMA-IR ≥ 1.5) and diabetes mellitus (DM). Multivariable logistic regression models were conducted to evaluate the association between abnormal glucose metabolism and impaired LVGLS (> - 16.65%)., Results: Forty-five (8.3%) participants had DM and 66 (12.2%) had abnormal HOMA-IR. LV mass index and E/e' ratio did not differ between participants with and without abnormal HOMA-IR, whereas abnormal HOMA-IR group had significantly decreased LVGLS (- 17.6 ± 2.6% vs. - 19.7 ± 3.1%, p < 0.05). The prevalence of impaired LVGLS was higher in abnormal HOMA-IR group compared with normal HOMA-IR group (42.4% vs. 14.0%) and similar to that of DM (48.9%). In multivariable analyses, glycemic abnormalities were significantly associated with impaired LVGLS, independent of traditional cardiovascular risk factors and pertinent laboratory and echocardiographic parameters [adjusted odds ratio (OR) 2.38, p = 0.007 for abnormal HOMA-IR; adjusted OR 3.02, p = 0.003 for DM]. The independent association persisted even after adjustment for waist circumference as a marker of abdominal adiposity. Sub-group analyses stratified by body mass index showed significant association between abnormal HOMA-IR and impaired LVGLS in normal weight individuals (adjusted OR 4.59, p = 0.001), but not in overweight/obese individuals (adjusted OR 1.62, p = 0.300)., Conclusions: In the general population without overt cardiac disease, insulin resistance carries independent risk for subclinical LV dysfunction, especially in normal weight individuals.

Cigarette smoking is closely associated with the development of cardiovascular diseases. However, the relationship between cigarette smoking and subclinical atherosclerosis has not been fully studied. We sought to clarify the association between cigarette smoking and carotid intima-media thickness (cIMT) in a general Japanese population. Among 1,209 participants who received a medical check-up with cardiovascular examination at our institution, 450 participants (37.2%) were smokers (including both past and current smokers). We evaluated cIMT as a marker of subclinical atherosclerosis. The value of cIMT and rate of carotid plaque defined as IMT ≥ 1.1 mm did not differ between smokers and never smokers. However, the rate of carotid high-risk atheroma, defined as carotid artery atheroma including hypoechoic dominant and ulceration, was significantly higher among smokers than never smokers (30.4%, vs 23.6%, p = 0.009). Even after adjustment for covariates, cigarette smoking was independently associated with high-risk atheroma formation (odds ratio 1.384, 95% CI 1.019-1.880; p = 0.038). The value of cIMT and the rate of high-risk atheroma were significantly higher in smokers than never smokers in the subgroup of participants aged ≥ 60 years, whereas the rate of high-risk atheroma only was higher in smokers than never smokers in the subgroup of participants aged < 60 years. In conclusion, the development of high-risk carotid artery atheroma may precede the thickening of cIMT in cigarette smokers, which suggests the novel insight for the pathological mechanism underlying cardiovascular events and cigarette smoking.